Method and apparatus for stripping well pipes



April 20, 1965 G. D. JOHNSON ETAL 3,179,177

METHOD AND APPARATUS FOR STRIPPING WELL PIPES Filed March 29, 1963 v 5 Sheets-Sheet 1 \NVENTORSi G. D. JOHN SON J. H. MC CARTHY THEIR AGENT April 20, 1965 's. o. JOHNSON ETAL- 3,179,177

METHOD AND APPARATUS FOR STRIPPING WELL PIPES Filed March 29, 1963 I s Sheets-Sheet 2 F IG. 3

FIG.2

FIG-7 FIG.

INVENTORS'.

e. 0. JOHNSON J. H. MC CARTHY BY: 5 ga.

THEIR AGENT April 0, 1965 G. D. JOHNSON ETAL 3,179,177

METHOD AND APPARATUS FOR STRIPPING WELL PIPES Filed March 29, 1963 s Sheets-Sheet a FIG.

FIG. l2

FIG. IO

INVENTORS'.

G. D. JOHNSON J. H. MC CARTHY BY I 5 uva THEIR AGENT United States Patent 3,179,177 METHOD AND APPARATUS FOR STRIIPING WELL PIPES Glenn D. Johnson, Downey, and John H. McCarthy, Orinda, Calif., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Mar. 29, 1963, Ser. No. 268,904 20 Claims. (Cl. 166-49) This invention relates to a method and apparatus for running pipe in and out of a well and pertains more par ticularly to a method of inserting into or removing from a well a string of pipe which surrounds a second string of pipe of a smaller diameter or a well tool which must be held in tension in the well to prevent it from dropping to the bottom of the well.

The operation of inserting a pipe into a well or removing it therefrom, when the pipe surrounds a second pipe or an elongated object already disposed within the well, is commonly referred to as stripping.

In an attempt to locate new oil fields an increasing amount of well drilling has been conducted at offshore locations, such, for example, as off the coast of Louisiana, Texas and California. As a general rule, the strings of casing in a well, together with the tubing string or strings, extend to a point well above the surface of the water where they are closed in the conventional manner that is used on land wells, with a conventional wellhead assembly being attached to the top of the casing. Attempts have been made recently to provide methods and apparatus for drilling, completing and working over a well wherein both the well casinghead and the various well components secured thereto or suspended therefrom are located underwater at a depth sufficient to allow ships to pass over them. Preferably, the casinghead and its as sociated equipment are located close tothe ocean floor. In order to install equipment of this type underwater in depths greater than the shallow depth at which a diver can easily operate, it has been necessary to design, entirely new equipment for this purpose.

In one such method of drilling offshore wells wherein a wellhead base structure is positioned on the ocean floor, strings of pipe, made up of many sections of pipe fastened together, are stripped in and out of the well by the method and apparatus of the present invention.

It is the primary object of the present invention to provide a method and apparatus, the apparatus being simple in design and easy to operate,'whereby a larger internaldiameter pipe may be stripped into a well over a smallerdiameter pipe or a well tool of smaller diameter.

/ A further object of the present invention is to provide apparatus for stripping pipe into an offshore well from a platform positioned above the ocean surface, while maintaining tension on an inner pipe string of smaller diameter "over which the larger diameter pipe string is being stripped. C

Another object of the present invention is to provide simple and safe apparatus adapted to be connected to and locked on an inner string of pipe to be heldin tension while an outer string of pipe is stripped over it.

' Still another object of the present invention is to pro- FIGURE 1 is a longitudinaldiagrammatic view illustrating cutaway sections of a derrick together with the hoist systems mounted in the'derrick in accordance with the present invention, p

FIGURES 2 through 7 are schematic views illustrating with reference 7 ice the stepwise operations of carrying out the method of the present invention;

FIGURE 8 is a longitudinal view taken in partial cross section of one form of a connector base to which a connector element and a hanger element have been secured;

FIGURES 9 and 10 are isometric views of the connector element and connector base, respectively, illustrated in FIGURE 8;

FIGURE 11 is an isometric view illustrating the hanger element engageable with the connector base of FIGURE 8; and

FIGURE 12 is a longitudinal view of an alternate form of a connector base in accordance with the present invention.

Referring to FIGURE 1 of the drawing, numerals 11 and 12 represent fragments of a well derrick, such for example as the type used in drilling wells, which would extend down to an operational base or floor 13, which may be the floor of a derrick or a floor of a drilling platform, either stationary or floatable, as used in drilling ofishore wells. The derrick 11-12 is provided with a conventional hoist system including a crown block 14, a traveling block 15 provided with a hook 15a and fall lines 16 running to a hoist 16a. Secured to the lower end of the traveling block 15 are elevator links 17 which suspend a conventional pipe-engaging elevator 18. The pipe connector or elevator 18 is designed to clamp around the upper end of a larger internal-diameter pipe string 20, or a section thereof, for raising or lowering the pipe string. In the event that the present hoist system is mounted on a floating drilling barge adapted to move up and down with relation to a wellhead positioned on the ocean floor, the hoist may be a constant tension hoist.

Positioned substantially axially within the larger-diameter outer pipe string 20a is a smaller-diameter inner elongated member such as a pipe string or cable 30 having a support and connector base 31 secured to the top thereof which is adapted to be locked to the connector element 28. The pipe string 20a is illustrated as extending through ahole 32 in the floor 13 of the derrick, and through a spider or rotary table 33 in which slips 34 are wedged in order to hang the pipe string 20a therefrom.

A hanger element 27 is adapted to seat in the open upper would be at least slightly below the lower end of a section of pipe 20 hanging in the elevators.

- In FIGURES 8 and 10, one form of a support and connector base 31 comprises a short cylindrical member adapted to be secured in any suitable manner, either fixedly or removably, to the smaller diameter inner elongated member or cable 30. A portion 36 of the cylindrical support and connector base 31 has a reduceddianieter thereby forming a seating shoulder 37 adapted to engage and hang from a landing surface 38 formed in the bore 39 of the hanger element 27.' Suitable con nector means are provided at the upper end of the support and connector base 31. These may take the form of an upwardly-extending connector arm 40 having a support pin 41 fixedly secured thereto and extending through thearm 40.

The connector element 28 is illustrated as being providedwith a pin slot 42 (FIGURE 8) which enters the body member' of the connector laterally, makes a generally right angle bend and then extends downwardly parallel to the axis of the connector 28. The support pin 41 is adapted to seat at the lower end of the pin slot 42 (FIGURE 9). As shown in FIGURE 9, the lower end of the connector 28 is provided with an upwardly-extending slot which is slightly wider than the connector arm 49 of the connector base 31. The lower end of the connector 28 may be curved, as at 44, in order to facilitate engagement of the support pin 41 in the pin slot 42 of the connector 28. The hoist cable 24 is secured to the top of the connector 28 in any manner well known to the art.

Any suitable type of hanger means may be employed which is of a size sufiicient to seat on the top of the larger-diameter outer pipe string 20a while being adapted to engage the seating shoulder 37 of the support and connector base 31 so as to temporarily support the inner elongated member 39. One form of a hanger element is illustrated in FIGURE 11 as comprising a body member 27 having an axial bore 33 extending vertically therethrough. At least a portion 390 of the bore 39 must be slightly smaller in diameter than the upper end of the connector base 31, that is, that portion of the connector base 31 above its seating shoulder 37. A longitudinal slot 46 extends through the wall of the hanger element body 27 so that the connector base 31 may pass through the slot and be positioned in the bore 39 of the hanger element 27. Preferably, the lower portion 45 of the hanger element body 27 is reduced in diameter to less than the internal diameter 47 (FIGURE 8) of the tool joint of the outer pipe string 26a so that the lower portion of the hanger element 45 nests within the tool joint while the flange 48 formed at the top of the hanger element 27 rests on the top of the pipe string 20a. The flange 48 is one form of stop means provided on the hanger element 27 which prevent it from falling into the pipe string 29a. If desired, the hanger element 27 may be provided with a handle 50 to facilitate handling of the hanger element 27 during pipe stripping operations in accordance with the present method.

Preferably, the upper portion of the bore 39 through the hanger element 27 is of a diameter slightly greater than the diameter of the upper portion of the support and connector base 31. At the same time the diameter of the bore 3'; in the lower part of the hanger element 27 is reduced as at 38 to a size slightly larger than the diameter of the support and connector base 31 below its seating shoulder 37, thus forming landing surface 38 within the bore 39 of the hanger element 27.

Thus, in engaging the hanger element 27 with the support and connector base 31, the entire hanger assembly 27 is moved forward so that the connector base 31 below its seating shoulder 37 enters the slot 46 of the hanger element until it is positioned in the bore 39 thereof. The slot 46 is wide enough to receive the connector base 31 below the seating shoulder 37 but not that portion above it. With the hanger element 27 surrounding the reduced diameter portion of the connector base 31 the entire assembly is lowered so that the hanger element 27 rests on the top of the outer pipe string 26a (FIGURE 3) and continued lowering of the cable 24 permits the seating shoulder 37 of the connector base 31 to land on the landing surface 38 of the hanger element 27. When seated in the manner the connector base 31 cannot be laterally displaced or removed from the hanger element 27 without first raising the support and connector base 31 until the seating shoulder 37 thereof clears the top of the hanger assembly 27.

Although the hanger element 27 has been illustrated as being of a configuration adapted to seat in the upper box end of a pipe section 20a, it is to be understood that the hanger element 27 can be altered in construction to be received in tubing, casing, drill pipe or other forms of pipe that may be required to be stripped into or out of a well. While the support and connector base 31 has been shown in FIGURE as being secured to the upper end of an inner elongated member in the form of a guide cable 39, it is to be understood that the connector head 31 could also be secured in any suitable manner, as by screw threads, to the upper end of a smaller-diameter pipe string to be held in tension while an outer pipe string or larger internal diameter 20a is stripped in or out of a well over the smaller diameter pipe.

In the event that the inner smaller-diameter pipe 51 has an upset end or box section 52 forming a shoulder 53 on the pipe, this shoulder 53 could be arranged to be seated on the landing surface 38 of the hanger element, or on the inner edge of the flange 38 surrounding the axial bore 39 through the hanger element 27. In thiscase a simple form of connector base could be employed which may be in the form of a threaded plug 54 adapted to be secured in the threaded upper end of the inner pipe string 51. The plug 54- Would be provided with a wrench head 55 and a connector arm 40a together with a support pin 41a which are similar to the connector arm 40 and support pin 41 described with regard to FIGURE 10.

In performing an operation in accordance with the present invention of stripping a larger-diameter pipe into a well over a smaller-diameter pipe or other inner elongated members such as a cable, the operation would start as illustrated in FIGURE 1 With the pipe 200 of larger internal-diameter being held by means of slips 34 in a fixed position within the spider or rotary table 33. At the same time the support and connector base 31 would have been secured to the top of the smaller-diameter inner elongated member or cable 30 and being supported by the hanger element 27 which rests on the open upper end of the outer pipe string 20:: of larger diameter Thus, both the outer pipe string 20:: and the inner cable 30 are held in tension as they extend from the operating platform 13 into a well therebelow.

Cable 16 is run off the hoist drum 1611. so that the traveling block 15 is lowered sutiiciently so that the elevators 18 can be connected to the upper end of a section of pipe 20 of larger internal-diameter to be added to the upper end of the pipe string 20a of the same diamcter being suspended from the slips 34 in the rotary table 33. The connector element 28 at the lower end of the suspending line 24 is run down through the pipe string or section 20 in a manner illustrated in FIGURE 1.

The traveling block 15 together with elevators 18, pipe section 20 and suspending line 24 are raised so that they are suspended directly above the pipe string 20a held in the rotary table 33. The connector 28 is then manually turned to a substantially horizontal position (FIGURE 2) so that the pin slot 42 (FIGURES 8 and 9) in the connector 28 can engage the pin 41 on the top of the support and connector base 31 in the manner shown in FIGURE 8.

With the connector 28 secured to the connector base 31, the traveling block 15 is raised by means of hoist drum 16a sufiiciently to pick up the connector base 31 far enough so that the hanger element 27 can be manually removed from around the connector base 31 (FIG- URE 3). The connector 28 and the connector base 31 together with the cables 30 and 24 are lowered down into the outer pipe string of larger diameter 20a with the upper end of the pipe string 20a and can be threadedly secured thereto (FIGURE 4). The traveling block 15 and all of the elements supported thereby are then raised slightly so that the slips 34 (FIGURE 1) can be disengaged from the outer pipe string 20a thus allowing the larger diameter outer pipe to be lowered down through the rotary table until the upper end of the newly-connected pipe section 20 (FIGURE 5) is just above the rotary table 33.

At this point slips are again inserted in the rotary table to suspend the pipe section 20 and the elevators 18 are disconnected from the upper end of the pipe section. The traveling block 15, elevators 18 and suspending cable 24 are then raised a distance sufficient to allow the support and connector base 31 to emerge from the top of the pipe section 20 (FIGURE 6) so that the hanger element 27 (FIGURE 11) can again be installed below the seating shoulder 37 of the support and connector base 31 in an "operation which is the reverse of that shown in FIGURE 3. The traveling block 15 would then be lowered slightly to allow the hanger element 27 to seat within the upper end of the pipe section and to allow the seating shoulder 37 on the support and connector base 31 to engage the landing surface 38 in the hanger element 27. With the inner elongated member or cable 39 again supported from the top of the large diameter pipe, tension would be relaxed on the suspension cable 24 allowing the connector 28 at the lower end of the cable 24 to be removed from the support and connector base 31 (FIGURE 7). By repeating the cycle of operations described, the desired amount of larger-diameter pipe can be stripped into a well over a smaller-diameter pipe or cable.

I To remove a larger internal diameter pipe from a well and strip it up oif a smaller-diameter pipe or cable, the above-described procedure would be reversed. After the suspending cable 24 and its connector 28 were positioned above the rotary table, the connector (FIGURE 7) would be secured to the upper end of the support and connector base 31 so that the weight of the inner pipe string or cable 30 could be transferred from the hanger element 27 to the suspending line 24. The traveling block would be pulled upwardly slightly to allow the support and connector head to emerge and permit the removal of the hanger element 27 (FIGURE 6). The traveling block 15, elevators 18 and suspending line 24 would then all be lowered until the elevators 18 could engage the upper end of the larger internal diameter pipe section 20. The traveling block 15 and elevator 18 would be raised so that the pipe string 20 and the suspending cable 24 were raised simultaneously a distance sufficient so that theentire length of the pipe section 20 was above the rotary table 33.

At this point the slips 34 would be again inserted in the rotary table 33 to suspend the larger-diameter outer pipe string while the upper section 20 thereof was unscrewed (FIGURE 4) sufliciently so that the traveling block 15 together with elevators 18 and pipe section 20 could be raised enough to allow the connector base 31 to emerge from the top of the pipe string 20a permitting installation of the hanger element 27 again. The traveling block would be lowered slightly to allow the Weight of the inner elongated member or cable 30 and its support and connector head 31 to be transferred from the suspending line 24 to the hanger element 27. With tension released on the suspending cable 24, the connector 28 would be disconnected from the support and connector head 31 and moved to one side so that the traveling block- 15 could be lowered to lay down pipe section 20 after which the elevators 18 would be dis connected and the suspending line 24 and its connector 28 pulled out of the pipe section 20. The cycle of operationscould then be repeated to strip other sec-t tions of pipe out of the well.

We claim as our invention:

l. A method of stripping a larger internal diameter outer pipe string over'a smaller-diameter inner elongated member which is axially movable, said method comprising the sequential steps of suspending temporarily said larger internal diameter outer pipe string,

(a) connecting a first suspending element to said inner member,

(b) anchoring and supporting said inner member within and in engagement with said larger-internal diameter outer pipe string,

(0) running a second suspending element through a section of larger internal-diameter outer pipe to be added to the top of said outer pipe string,

(d) jointly suspending and moving said pipe section to be added and said second suspending element carried therein into substantial longitudinal position above said suspended outer pipe string,

(e) connecting said second suspending element to said inner member, v r

(f) transferring the weight of said inner member from said first suspending element to said second suspending element,

(g) disengaging said inner member from supported engagement with said outer pipe string,

(h) removing said first suspending element from engagement with said inner member,

(i) lowering said larger internal-diameterpipe section into engagement with said outer pipe string while lowering said inner member in tension within said outer pipe string, and i (1') connecting the pipe section to the outer pipe string.

2. The method of claim 1 wherein the weight of said inner member is transferred to said second suspending element by applying tension to said second suspending element.

3. The method of claim 1 wherein the smaller-diameter inner elongated member is supported within the open upper end of said larger-internal diameter pipe string by landed contact of said first suspending element thereon.

4. The method of claim 2 wherein tension is applied to said second suspending element by raising said second suspending element.

5. The method of claim 1 including the steps of lowering said outer pipe string and said inner member simultaneously a distance substantially equal to the pipe section added, and anchoring the outer pipe string against further downward movement.

6. The method of claim 5 including the subsequent step of raising the inner member until the top thereof emerges from the top of the outer pipe string.

7. The method of claim 1 including the step of raising the inner member an amount sufficient to remove said first suspending element prior to disconnecting said first suspending element from engagement with said inner member.

8. A method of stripping a larger internal-diameter pipe string down over a smaller-diameter pipe string having at least the lower end thereof positioned within a well, said method comprising the sequential steps of (a) tixedly suspending said larger internal-diameter outer pipe string by engaging the outer surface thereof,

(b) attaching a supportand connector base to the top of the inner pipe string, l t

(a) connecting a hanger element to said support and connector base,

(d) hanging said inner pipe string from the top ofsaid larger internal-diameter pipe string,

(e) running a suspending cable through a section of largerinternal-diameter outer pipe to'be added to the top of said outer pipe string,

.(f) jointly suspending and'moving said outer pipe section with. said suspending cable positioned substantially concentrically therein into substantial longitudinal position above .said suspendedouter pipe string,

(g) connecting the lower end ofsaid suspending cable to said support and connector base,

(it) raising said pipe section and said second suspending cable simultaneously to suspend the inner pipe string from said cable, I

(i) disconnecting said hanger element from said sup- .port and connector base,

(j) lowering the larger internal-diameter pipe section into engagement with said suspended outer pipe string and connecting the pipe section to said outer pipe string,

(k) simultaneously lowering said inner and outer pipe strings a distance substantially equal to the pipe section added, and

(I) again suspending said outer larger-internal diameter pipe string independent of said smaller diameter pipe string.

9. The method of claim 8 including the subsequent step of raising the inner pipe string in suspension until the support and connector base thereof is above the top of the outer pipe string.

10. A method of stripping a larger internal-diameter outer pipe string up over a smaller-diameter axiallymovable inner elongated member, said method comprising the sequential steps of (a) fixedly suspending said outer pipe string from the outer surface thereof,

(b) connecting a first suspending element to said inner elongated member to suspend said inner member therefrom,

(c) lowering said first suspending element and said smaller-diameter inner elongated member into said larger internal-diameter outer pipe string a distance substantially equal to a pipe section of said outer pipe string,

(d) engaging said larger internal-diameter outer pipe string above its suspension point and simultaneously raising said inner elongated member and said outer pipe string until at least one section of the outer pipe string is above its previously-suspended position,

(2) again fixedly suspending said outer pipe string at a point below the uppermost pipe section thereof,

(f) disconnecting at least one pipe section from the top of said outer pipe string,

('g) raising said disconnected pipe section until at least the top of the inner member is exposed,

(/1) engaging said inner elongated member with a second suspending element,

(1') hanging said second suspending element from the open upper end of said outer pipe string with said inner elongated member within said outer pipe string, and

(j) disconnecting said first suspending element from said inner elongated member.

11. The method of claim 10 including the subsequent steps of moving said large internal-diameter pipe section to one side of said suspended pipe string, and withdrawing said first suspending element from said pipe section.

12. Apparatus for use in well operations for selectively stripping to or from a well a large internal-diameter pipe string over a smaller-diameter inner elongated member held in tension throughout the operation, said apparatus comprising (a) an operational and support base positioned adjacent said pipe string,

(b) hoist means including hoist cable means having a portion arranged for vertical movement above said pipe to be stripped out of the well,

(c) connector means secured to the end of said hoist cable means, said connector means including (d) a first connector of a size adapted to connect to the upper end of said large internal-diameter outer pipe string,

(e) a second connector of a size to connect to said inner elongated member and pass through said outer pipe string and being of a length sufiicient to extend beyond said first connector a distance greater than a section of pipe in said outer pipe string,

(1) independent hanger means engageable with the upper end of said small-diameter inner elongated member and being of a size to hang on the upper end of said larger internal-diameter outer pipe string, and

(g) slip-type anchoring means for engaging the large internal-diameter outer pipe string selectively and temporarily secure it relative to said base against axial movement.

13. The apparatus of claim 12 wherein said first connector is a pipe-engaging elevator secured to a traveling block.

14. The apparatus of claim 13 wherein said second connector includes a flexible cable secured to a traveling block of said hoist means and arranged to depend therefrom in concentric arrangement within said elevator and having means at the lower end thereof for engaging the upper end of said inner elongated member.

15. The apparatus of claim 12. wherein said inner elongated member is provided with a seating shoulder means of a diameter greater than that portion of said member immediately below it, and wherein said hanger means is of a size to engage said inner elongated member below said seating shoulder means thereof, said hanger means having at least a portion thereof extending laterally over a distance greater than the diameter of said outer pipe string so as to seat thereon.

16. The apparatus of claim 15 wherein said hanger means comprises a body member having an axial bore therethrough and a longitudinal slot through the body member in communication with said bore, said bore diameter and slot width being slightly greater than the outer diameter of said inner elongated member just below the seating shoulder thereof and less than the diameter of said seating shoulder whereby said shoulder cannot pass through said axial bore.

17. The apparatus of claim 16 wherein the lower portion of said hanger means is of a diameter to fit within the open upper end of said large internal-diameter pipe string.

18. The apparatus of claim 16 wherein said axial bore through said body member is enlarged in the upper portion thereof to a diameter greater than that of said seating shoulder means near the upper end of said inner elongated member.

19. The apparatus of claim 15 including a short cylindrical member secured to the upper end of said inner elongated member and wherein the seating shoulder means thereof are formed on said cylindrical member.

20. The apparatus of claim 19 including a mating connector carried on the upper end of said cylindrical member for connection to said second connector of said connector means carried by said hoist cable means.

References Cited by the Examiner UNITED STATES PATENTS 2,758,654 8/56 Simmons 116-49 X 2,782,004 2/57 Harrigan 166-46 X 2,998,067 8/61 Kerver 166-46 1 3,100,015 8/63 Regan l6646 CHARLES E. OCONNELL, Primary Examiner. 

